Site-directed mutagenesis study on the glucose 1-phosphate binding site of potato tuber adpglucose pyrophosphorylase

Yingbin Fu, Miguel A. Ballicora, Jack Preiss

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Chemical modification and site-directed mutagenesis studies identified that Lys-195 in ADPGlc PPase from E.coli was involved in the binding of substrate glucose 1-P (Glc 1-P) . This residue is highly conserved in every bacterial and plant ADPGlc PPase sequenced to date . In the previous work, it was suggested that the small subunit of the potato tuber ADPGlc PPase might act primarily as a catalytic subunit, while the large subunit as a regulatory subunit. However, it was still quite possible that the Glc 1-P binding site is shared between the large and small subunits. Site-directed mutagenesis was used to discriminate these possibilities. It was found that the Km value for Glc 1-P of the wild type tuber enzyme increased 200-, 550-, 780 -fold by changing the putative lysine residue ( Lys-198 ) to Arg, Ala, Glu, respectively. This indicates that this Lys residue in the smalt subunit performs the same role as the corresponding Lys residue in E.coli. ADPGlc PPase. Site-directed mutagenesis studies on the conserved lys residue on the large subunit of the tuber enzyme will be done in the near future.

Original languageEnglish (US)
JournalFASEB Journal
Issue number6
StatePublished - 1996
Externally publishedYes

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Cell Biology


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